#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

int main()
{
    float a, b, c, d, e;
    scanf("%f%f%f%f%f", &a, &b, &c, &d, &e);
    float f;
    f = (a + b + c + d + e) / 5.0;
    printf("%.2f", f);
    return 0;
}